<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>05流程控制</title>
</head>
<body>
<script>
  //1.顺序结构
  console.log(1);
  console.log(2);
  console.log(3);
  //2.分支结构
  let username = '露娜';
  if(!username){//若用户名为空字符串,转为布尔是false,!false为true,走分支1
      alert('用户名不能为空!');
  }else{
      alert('欢迎'+username+'回来!');
  }
  //3.选择分支
  let gender = 1;
  switch (gender){
      case 1:
          console.log('先生');break;
      case 0:
          console.log('女士');break;
      default:
          console.log('保密');
  }
  //4.循环结构
  let names = ['张三','李四','王五','赵六','钱七'];
  for(let i=0;i<names.length;i++){
      console.log(names[i]);
  }
  console.log("******************");
  console.log(i);
  //增强for循环 names表示当前要遍历的集合/数组
  //let n表示本轮遍历到的元素
  for(let n of names){
      console.log(n);
  }
</script>
</body>
</html>